Lining for kilns



A. F. MEYERHOFEm LINING- FOR KILNS. APPLICATIQN FIL/ED JUNE F6, |914. RENEWED OCT. 23,1920.

OUTER /flLN WALL- UNITED STATES- PATENT OFFICE.

ALBERT FRITZ MEYEBHOFEB, 0l MANNHEIM, GERMANY, ASSIGNOB TO DYNAIIDON G. I. B. H., 0F IANNHEm-WALDHOF, GERMANY, A, FIBI.

LDSING FOB KILNS.

Specification of Letters Patent.

Patented May 17, 1921.

Application led June 16, 1914, Serial No. 845,389. Renewed October 23, 1920. Serial No. 419,074.1.

To all whom it may concern.;

Be it known that'I, ALBERT FRITZ MEYER- HorER, citizen of the Republic of Switzerland, residing at- F riedrchsring, Mannheim, in the Grand Duchy of Baden, Empire of Germany, have invented certain n ew and useful Improvements in- Linings for Kilns: and I do hereby declare the fol-` lowing to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to kiln or furnace linings. and in particular to the linings of rotary tubular, or cylindrical, kilns, such as are used especiallyr in the manufacture o f cements.

The object of the invention is to increase the the-rmic etliciency of such kilns, or furnaces, by providing them with linings in such a way as to materially reduce, or substantially eliminate. the radiation and conduction of heat therefrom. In the kilns, or furnaces, of this character heretofore employed it has been found that a considerable amount of heat is lost and goes to waste by the radiation which occurs, particularly at that portion of the furnace known as the sintering zone. To obviate this loss of heat. it has been proposed heretofore to provide the fire-brick lining of the kiln atthe sintering zone with a backing layer of a second heat-refractory heat-insulating material. That arrangement of materials, however,` did not result in any practical advantage for the reason that it facilitates the attack on. and destruction of, the fire-refractory lining to a much greater extent than if such heat-insulating material were not employed in connection with the lining heretofore used. As is known, in the operation of such kilns as` heretofore constructed the chemi'cal action of the clinkers on the fire-refractory lining in the zone of highest temperature leads to the formation of a.` ux. which. however. solidifes at a certain depth of the lining in consequence of the lower temperature there prevailing, due to v heat radiation and conduction, and thus forms a protecting layer against further attacks. This automatic protective action is. however. absent when the usual kiln lining is backed with a heat-insulating material as above roposed. In this case the lining is heated, to the same high temperature to its entire depth, and hence the flux formed by the action of the clinkers is not solidified at any depth, and the corrosive and destructive action of the clinker on the lining continues throughout the entire thickness of the same.

I have found that these objectionable results, due to the introduction of a heat-insulating backing at the sintering zone, may be avoided by lining the kiln with refractory bricks made from a mixture of corundum and a binder such as clay, and containing a high percentage (over 60 per cent.) of alumina, (aluminium oxid A1203). Such a material is prepared, or example, -according to S. Patent No. 100673, that is to say, by mixing corundum, either the natural mineral or the artificial material obtained by previously fusing alumina, in suitable granular form, with a. binder lof clay to form a plastic mass. the lining bricks, or blocks, being then formed and burnt in the usual or any suitable way. Lining bricks made from such' material exhibit the surprising property of not being attacked by the clinkers at the high temperatures prevailing in the rotary cement kilns, or furnaces, even when they are backed with heatinsulating layer for preventing the outward radiation of heat as above described. This newly discovered property of lire-refractory linings made of such material was not at all to be expected from the existing prior knowledge in this art, and it furnishes a very convenient means of providing kilns of while eliminating the disadvantages which heretofore resulted therefrom.

In carrying out my invention I arrange between the lining composed of bricks made from a mixture of corundum and clay and the walls of the kiln. a heat-insulating layer of suitable material, such as asbestos, porous stones, or the like, in such thickness that when the kiln is in operation the outer surface of the kiln is, at the highest, only as warm as the human hand.

To give an example of what I consider the best manner of carrying out my invention, I would state that a very effective and serviceable kiln or furnace lining, made under my said invention, is made of material comprising four parts of previously fused A1203 (corundum) and one part of a binder of clay or aluminiferous material, and is of a thickness of about 12 centimeters,

said lining being combined with a backing layer having a thickness of 8 centimeters, and made from porous insulating stone, such, for example, as is employed for blastheaters or cowpers. As is known, such 4porous Cowper bricks or stones are prey pared from a mixture of clay with a comminuted combustible substance, such as sawdust, and then firedv in a kiln, under which treatment the combustible substance is con sumed, leaving the burnt brick in a porous condition.

As a modification there may be employed a layer of 15 centimeters in thickness of the said fused material comprising four parts of corundum combined with one part of a binder of clay in connection with a 'heatinsulating backing layer of a thickness of 5 centimeters and composed of asbestos.

Instead of the clay or aluminiferous binder employed as above indicated in the manufacture of my new kiln lining, other binders may be employed such as lime or a hydraulic binder containing considerable quantities of lime, an important point being, that the liningl material contains a high percentage of previously fused alumina.

It will be noted from the above examples that the two layers combined attain only the,

' layer 2 and heat insulating layer 3 interposed between the two.

What Iclaim, Letters Patent, is

1. A lining for the purposes set forth, which consists of an inner layer containing a high percentage of corundum, combined with an insultaing outer layer.

2. A lining for the purposes set forth, which consists of an inner layer of a material formed from corunduin combined with a binder, in combination with an outer heatinsulating layer.-

3. A lining for the purposes/set forth,-

, which consists of an inner layer of a matesulating layer.

rial formed from corundum combined with clay, 1n combination with an outer heat-in- 4. A lining for the purposes set forth, which consists of an inner la er containing a high percentage of the ar cial substance consisting of previously fused alumina,

combined with an insulating outer layer.

`5. A lining for the purposes set forth,

and desire to secure byV which consists of an inner layer of a material. formedy from the artificial substance consisting of previously fused alumina combined with a binder, in combination with an outer heat-insulating layer.

6. A lining for the purposes set forth,

which consists of an inner layer of a matedum; and an insulating layer interposed between the outerwall and the inner layer.

8. In a kiln, an outer tubular wall, in

combination with an inner heat-refractory lining layer of a material comprising corundum combined with a binder; and an insulating layer arranged between the outer wall and the inner layer. 9. In a kiln, an outer tubular wall, in combination with an inner heat-refractory lining layer of a material comprising corundum combined with clay; and an insulating layer arranged between the outer wall and the inner layer.

10. In a kiln, an outer tubular wall,-in combination with an inner heat-refractory layer containing a high percentage of the artificial substance consisting of previously fused alumina; and an insulating layer interposed between the outer wall and the inner layer.

11. In a kiln, an outer tubular wall, in combination with an inner heat-refractory lining layer of aA material' comprising-the artificial substance consisting of previously fused alumina combined with a binder; and` an insulating layer arranged between the outer wall and the vinner layer.

12. In a kiln, an outer tubular wall, in combination with an inner heat-refractory lining layer of a material comprising the artificial substance consisting of previously yfused alumina combined with clay; and an insulating layer arranged between theouter wall and the inner layer.

13. A lining for the purposes set forth which consists of an inner layer containing a`- high percentage of corundum combined with an insulating layer of porous brick.

14. A lining for the purposes set forth which consists of an inner layer containing a high' percentage of corundum combined with an insulating layer of porous Cowper brick.

In testimony whereof I hereunto aflix my signature in theV presence of two Witnesses.

` ALBERT FRITZ MEYERHOFER.

WitiesseszM f nrrz onLLnn,

HANS WINKIER, 

